Sometimes you are in a context when handling the mail is not effective, possible or reasonable. You may need to wait to a certain time, be in a certain place, or have certain resources or pre-requisites. For those emails you can defer the handling. BlueMail has ready made time frames set for you: later today, end of day, next day / week/ month, or someday in the future. You can also pick a specific date/time, which is useful when you know exactly when would be the most suitable time to handle this mail.
Note: that if you use the Incoming Filter you won’t see emails marked as Snooze+.